This Program Project is to pursue the study of the effects of growth factors on different cell systems with a major emphasis on hemolymphopoietic growth factors. The Project brings together a group of collaborating investigators with different backgrounds and expertise. Drs. Charles Emerson and Sonia Pearson-White are molecular geneticists who have a particular interest in developmental biology, Dr. Peter Isakson is a cellular immunologist with an interest in B cell development, Dr. Peter Quesenberry is a research hematologist with a life-long interest in hemopoietic growth factors, Dr. Gary Balian is a protein biochemist with a particular research thrust directed towards extracellular matrix and collagen studies and Dr. Julie Sando a molecular pharmacologist with a major focus on second messenger signalling and the control of growth control. These different principal investigators or core directors in varying ways have been interacting with one another as demonstrated by co- publications, shared grants and ongoing collaborative research. The major them of this Program Project related to the effects of growth factors on hemolymphopoietic cells although one project extends this to the muscle system. Dr. Julie Sando will be studying the mode of control of granulocyte-macrophage colony stimulating factor production by cells, Drs. IsaKson and Quesenberry will be concentrating on the action of growth factors in stimulating various classes of cell and Dr. Emerson's project involves study of nuclear proteins which may be determining the action of growth factors on muscle lineages. Dr. Balian will be addressing the role of extracellular matrix and collagen in potentially influencing many of these growth factor interactions. These investigators bring multiple different viewpoints and skills to each others'projects. The two core projects involving molecular genetics and cell culture will be used extensively by all projects and will enhance greatly the ability to carry on cutting edge research by the group as a whole. This Program Project will allow many of the investigators to progressively pursue areas in molecular genetics that might otherwise not be open to them and other investigators to enter into the fields of growth factor control of cell growth and second messenger signalling. Thus, the result of the five projects working under this Program Project should be yield significantly grater than would be seen with the individual projects working separately.